Hydrated Food

ABSTRACT

Providing a hydrated food which contains theanine and in which theanine content can stably be maintained even when the hydrated food is preserved for a long period of time and the taste threshold of the food can be improved and the peculiar taste can be flavored. The problem can be overcome by a hydrated food containing theanine and pyroglutamic acid. In this case, it is preferable that pH ranges from about 2.8 to about 7.5. Furthermore, it is preferable that a content of pyroglutamic acid ranges from about 1% to about 20% relative to a content of theanine.

TECHNICAL FIELD

The present invention relates to a hydrated food containing as activeingredient pyroglutamic acid and theanine. Furthermore, the inventionrelates to a hydrated food which can stably maintain a content oftheanine during preservation and improve a taste threshold by thepresence of pyroglutamic acid in a solution of theanine, glutamine orglutamic acid. Still furthermore, the hydrated food can improve tastepeculiar to branched chain amino acids, synthetic sweeteners andpeptides.

BACKGROUND ART

Theanine used in the present invention has effects of mood disordercuring, mind concentration improving, difficult menstruationsuppression, flavor improvement composition and sleep facilitation, andthus, it is known that theanine has beneficial physiological effects.However, in order that the physiological effects may be experienced, 20cups of tea need to be taken per occasion as an intake for adult.Accordingly, it is substantially impossible to take theanine from onlytea. Development of a hydrated food containing theanine has been desiredfor the purpose of easily taking theanine. However, when theanine ispreserved in a water-soluble liquid composition, theanine is decomposedwith progress of time, whereupon there is a problem that a content oftheanine is reduced when a hydrated food containing theanine ispreserved for a long period of time.

Furthermore, when melted into a high concentrated state, theanine hasits peculiar taste though theanine is a highly seasoned amino acid.Every taste has a threshold, which is the minimum concentration at whichtaste sensitivity to a particular substance or food can be perceived.Theanine has a threshold of 150 mg/100 ml, glutamine has a threshold of250 mg/100 ml, and glutamic acid has a threshold of 5 mg/100 ml. Valinehas a threshold of 150 mg/100 ml, leucine has a threshold of 380 mg/100ml, and isoleucine has a threshold of 90 mg/100 ml. Taste is perceivedwhen the concentration is equal to or higher than the threshold. Thetaste sometimes affects the hydrated food. Furthermore, acesulfame K,aspartame and L-phenylalanine all of which are synthetic sweeteners haverespective unique bitterness. Some peptides also have bitterness atabout 1000 mg/100 ml.

On the other hand, for example, patent document 1 discloses a techniquefor utilizing pyroglutamic acid as food. As disclosed, when pyroglutamicacid is contained in a frozen food, a period of time necessary forfreezing and thawing the food is shortened and freezing denaturation offood can be suppressed. However, few things are generally known aboutthe effects of pyroglutamic acids.

[Patent document] JP-A-H08-47383

DISCLOSURE OF THE INVENTION Problem to be Overcome by the Invention

An object of the present invention is to provide a hydrated food whichcontains pyroglutamic acid and theanine and in which a stable content oftheanine can be maintained even when the hydrated food is preserved fora long period of time and which can increase the threshold of food andflavor the peculiar taste.

Means for Overcoming the Problem

The inventors made repeated investigations in view of the above objectsand found that the content of theanine in a hydrated food was stabilizedby the use of pyroglutamic acid in the hydrated food containingtheanine. In particular, when pH of the hydrated food ranges from about2.8 to about 7.5, stable content of theanine can be maintained eventhough the hydrated food is a beverage or gel-food. Furthermore, theinventors found that the taste peculiar to theanine was reduced even ina solution in which theanine more than a threshold of amino acid isdissolved and food having bitterness could be flavored, therebybasically made the invention.

More specifically, the present invention is each of the following (1) to(5):

(1) A hydrated food characterized by containing (A) pyroglutamic acid;

(2) A hydrated food characterized by containing one or more amino acidsselected from groups comprising (A) pyroglutamic acid, (B) theanine,glutamine and glutamic acid;

(3) A hydrated food characterized by containing one or more amino acidsselected from groups comprising (A) pyroglutamic acid, (B) theanine,glutamine and glutamic acid, and (C) branched chain amino acid;

(4) A hydrated food characterized by containing one or more amino acidsselected from groups comprising (A) pyroglutamic acid, (B) theanine,glutamine and glutamic acid, and one or more synthetic sweetenersselected from a group of (D) acesulfame K, aspartame andL-phenylalanine;

(5) A hydrated food characterized by containing one or more amino acidsselected from groups comprising (A) pyroglutamic acid, (B) theanine,glutamine and glutamic acid, and (E) peptide;

(6) The hydrated food according to any one of (1) to (5), characterizedin that the hydrated food is a beverage having pH ranging from about 2.8to about 7.5; and

(7) The hydrated food according to any one of (1) to (5), characterizedin that the hydrated food is a gel food having pH ranging from about 2.8to about 7.5.

A pyroglutamic acid used in the present invention is also known aspyrrolidone carboxylic acid (2-pyrrolidone-5-carboxylic acid) and is aderivative of amino acid having a molecular formula of C₅H₇NO₃ and amolecular weight of 129. The substance is present in sufficient quantityin Steffen's Waste which is a byproduct in the manufacture of sugarbeet. When L-glutamic acid is hydrolyzed at 175° C., partially racemizedpyroglutamic acid is obtained. Furthermore, when L-glutamicacid-γ-methyl ester or L-glutamic acid-γ-ethyl ester is left in methanolsaturated with ammonia, optically pure pyroglutamic acid can readily beobtained. The obtained pyroglutamic acid has a rhombic column crystaland a melting point ranging from 159° C. to 160.5° C., and is an easilywater-soluble substance.

Pyroglutamic acids have conventionally been used as seasoning(JP-A-2001-299266) and sound hair agent (JP-A-2001-81013). However,applications to stabilization of beverage and flavoring have beenunknown.

The pyroglutamic acid used in the present invention can be used as salt.The salt should not be limited to a specific one and monovalent,bivalent or trivalent salt can be used. In particular, it is preferableto use monovalent salt (preferably, potassium chloride or sodiumchloride).

A pyroglutamic acid obtained by any method is available as thepyroglutamic acid used in the present invention. For example, thepyroglutamic acid may be extracted from a plant such as sugar beet orisolated from a hot-water extract of various animals or may be aderivative from glutamic acids, glutamine or the like.

The pyroglutamic acid used in the present invention has a contentranging from about 0.0003% to about 40% relative to total mass of thehydrated food.

Theanine used in the present invention is known as a principal componentof deliciousness of green tea and is an important substance as a flavorcomponent of food such as tea. Methods of making theanine used in theinvention include a method of extracting theanine form tea leaves, amethod of obtaining theanine by organic synthesis reaction (Chem. Pharm.Bull. 19 (7) 1301-1307 (1971)), a method of causing glutaminase to reactagainst a mixture of glutamine and ethylamine thereby to obtain theanine(JP-B-H07-55154), a method of culturing culture cells of tea in aculture medium containing ethylamine and facilitating growth of culturecells while an amount of theanine stored in the culture cells is beingincreased (JP-A-H05-123166), substituting ethylamine derivative such asmonoethylamine hydrofluoride for ethylamine, thereby obtaining theanine(JP-A-2000-026383) and the like. Theanine may be obtained from any oneof the above-described methods. Green tea, oolong tea, tea and the likeare exemplified as the leaves of tea. Any one of L-, D- and DL-theaninemay be used. L-theanine is preferable in the invention since it isparticularly recognized as food additives and is economic in use.

Furthermore, the theanine used in the invention may be any one of arefined product containing 98% or more of theanine, rough refinedproduct with content of theanine ranging from 50% to 98% and extractwith content of theanine ranging from 10% to 50%.

Theanine used in the invention has a high security. For example, in anacute toxicity test with use of mice, no mice died and abnormality wasfound in an ordinary state, weight and the like even in the case of oraladministration of theanine by 5 g/kg. Furthermore, theanine is known asa principal component of deliciousness of tea and used as a foodadditive for use as gustatory. An amount of theanine to be added is notlimited under the Food Sanitation Law.

Glutamine in the present invention is a 2-aminoglutalamid acid andbecomes glutamic acid by acid hydrolysis. Glutamine is classified intopolar non-charged side-chain amino acids or neutral polar side-chainamino acids. Glutamine is one of amino acids composing protein which iscontained in a large amount in extracellular fluid of animals and is anon-essential amino acid. However, since a rise of catabolism such asmetabolic stress sometimes renders an amount of glutamic biosynthesis inthe body short, glutamine is treated as quasi-essential amino acid.Glutamine in the invention is synthesized from glutamic acid by theaction of glutamine synthetase (glutamic acid ammonia ligase, EC6.3.1.2). However, glutamine may be manufactured by anothermanufacturing method.

Glutamine in the present invention is a 2-aminoglutalamid acid and wasfirst found from hydrolysate of wheat gluten. Monosodium glutamate (MSG)which is sodium salt of glutamic acid is used as a chemical seasoning.Glutamic acid is classified into acidic polar side-chain amino acids.Glutamic acid is one of amino acids composing protein and anon-essential amino acid. Glutamic acid also functions as aneurotransmitter in animal bodies. A sea tangle, cheese, green tea andthe like are known to contain a large amount of glutamic acid. Amushroom, tomato, sea food and the like are also known to contain alarge amount of glutamic acid.

Glutamic acid in the invention is synthesized by causing 2-oxoglutaricacid in a citric acid cycle to receive an amino group from another aminoacid by the action of glutamic transferase or by reverse reaction ofdegradation of glutamic acid into 2-oxoglutaric acid and ammonia byglutamate dehydrogenase (EC 1.4.1.3). Glutamic acid is primarily usedfor manufacture as an intermediate material of monosodium glutamatewhich is a food additive. Since glutamic acid itself has acidity,neutralized sodium salt is used as a seasoning.

Glutamic acid in the invention may be obtained by any one of methods ofproducing by amino-acid fermentation of microbe with molasses or rice,cornstarch and ammonium chloride serving as materials; obtaining byadding hydrochloric acid to vegetable albumin such as soybean albumin orgluten and hydrolyzing the addition in a high temperature atmosphere;extracting, by the Steffen process, waste molasses produced in theprocess of making beet sugar from beet; separating L-glutamic acid fromDL-glutamic acid obtained by carboxylation, cynoamin, or hydration ofacrylonitrile as a material; and amino-acid fermentation of microbe bythe action of coenzyme and enzyme such as glutamate dehydrogenase, aminotransferase or the like with molasses or rice, cornstarch and ammoniumchloride serving as materials.

Branched amino acid in the invention is Valine, leucine or isoleucine.The branched amino acid has a structure that a chain of carbon (methylgroup: —CH₃) is branched. These three amino acids are named generically“branched chain amino acid” (BCAA). The branched chain amino acid is anessential amino acid and occupies about 50% of essential amino acidscontained in food protein and about 35% of essential amino acidscontained in protein of muscle. Furthermore, the branched chain aminoacid performs an important role as a material for muscles (protein) of ahuman body and as an energy source during physical activities. Thebranched chain amino acid is metabolized in muscles. Upon a hardphysical activity, glucide is first used as an energy source. When theglucide has been consumed, protein in muscles is decomposed intobranched chain amino acids, which are used as an energy source.

Thus, the branched chain amino acid is easy to be converted to energy.It is known that the branched chain amino acid suppresses reduction inmuscles and muscle weakness, makes up for stamina and increasesendurance. Furthermore, it is known that the branched chain amino acidhas effects of smoothly reproducing muscles and suppressing a value ofblood lactic acid as a fatigue-producing substance to prevent muscularfatigue and suppressing increase in serotonin as neurotransmitter in thebrain to prevent tired feeling and reduction in vigor and powers ofconcentration. Valine of the branched chain amino acid is known to havefunctions of adjustment of nitrogen balance, promotion of growth andadjustment of nervous system as well as metabolic promotion and afunction as energy source. Leucine promotes synthesis of skin, bone andmuscle and suppresses degradation of muscular organization andaccordingly has effects of recovering from fatigue, increasing thephysical strength, improving liver functions and adjusting blood glucoselevel. Isoleucine is known to have effects of promoting growth,adjusting functions of nerve system, expanding blood vessels andimproving liver functions.

Acesulfame K (acesulfame potassium) is an artificial sweetener made froma material of “diketene” which is also used as dyes and pigments andsynthetic material of pharmaceuticals. Acesulfame K is 200 times sweeterthan sugar and has a high heat resistance and is stable. Acesulfame Kreceived approval as a food additive in 2000 in Japan.

Aspartame in the invention is an ester of aspartic acid, phenylalanineand methanol and is about 200 times sweeter than sugar.

L-phenylalanine in the invention is a glycogenic essential amino acidand is known to become a synthetic material for a neurotransmitter ofnoradrenaline and dopamine in the brain. These synthetic sweeteners havepeculiar bitterness as an aftertaste.

Peptide in the invention is a polymer of two or more amino acids and isobtained by synthesis or degradation of protein. The peptide is naturalor synthetic and contains hydrolysate of protein and fraction thereof.The peptide is a simple or a mixture of them or a mixture of amino acidand peptide.

As the hydrated food of the invention is exemplified a preferredbeverage, refreshing beverage, carbonated beverage, fruit beverage,lactic acid drink, lactic beverage, sports drink, diet drink,supplementary beverage, alcohol-containing beverage, liquid beverage orsolid jerry both made by blending gelatinizing agent and the like. Thehydrated food of the invention, should not be limited particularly,designates all the beverages containing water. A water content shouldnot be limited and is normally not less than 50%, preferably not lessthan 80%, more preferably not less than 90%, and most preferably notless than 90%.

The hydrated food of the invention has pH ranging from about 2.8 toabout 7.5, preferably ranging from about 4.3 to about 7.0, furtherpreferably ranging from about 5.0 to about 6.0. The pH is adjusted inthe range so that a content of theanine in the hydrated food is easy tobe maintained stably for a long period of time. A pH adjusting agentshould not be limited. For example, as the pH adjusting agent can beused a food additive such as a citric acid, malic acid, tartaric acid,phosphoric acid, maleic acid, ascorbic acid or acetic acid and a naturalsubstance such as lemon.

The hydrated food of the invention contains theanine whose concentrationranges from about 0.03 mg/mL to about 250 mg/mL, preferably ranges fromabout 0.3 mg/mL to about 250 mg/mL, more preferably ranges from about1.5 mg/mL to about 250 mg/mL. When the concentration exceeds 250 mg/mL,the theanine cannot be dissolved since the value is an upper limit ofdissolution.

Pyroglutamic acid and theanine both contained in the hydrated food ofthe invention have a mass ratio (that is, pyroglutamic acid/theanine)ranging from about 0.1% to about 200%, preferably ranges from about 0.5%to about 100%, more preferably ranges from about 5% to about 50%. Whensuch an amount of pyroglutamic acid is added to the hydrated food, thetheanine can stably be maintained at a predetermined content for a longperiod of time, whereupon a taste peculiar to theanine is easy toreduce.

In order that glutamine may be flavored in the hydrated food of theinvention, pyroglutamic acid and glutamine have a mass ratio (that is,pyroglutamic acid/glutamine) ranging from about 0.05% to about 100%,preferably ranges from about 0.1% to about 50%, more preferably rangesfrom about 1% to about 30%. When such an amount of pyroglutamic acid isadded to the hydrated food, a taste peculiar to glutamine is easy toreduce.

In order that glutamic acid may be flavored in the hydrated food of theinvention, pyroglutamic acid and glutamic acid have a mass ratio (thatis, pyroglutamic acid/glutamic acid) ranging from about 3% to about6000%, preferably ranges from about 15% to about 3000%, more preferablyranges from about 150% to about 1500%. When such an amount ofpyroglutamic acid is added to the hydrated food, a taste peculiar toglutamine is easy to reduce.

In order that valine acid may be flavored in the hydrated food of theinvention, pyroglutamic acid and valine have a mass ratio (that is,pyroglutamic acid/valine) ranging from about 0.1% to about 200%,preferably ranges from about 0.5% to about 100%, more preferably rangesfrom about 5% to about 50%. When such an amount of pyroglutamic acid isadded to the hydrated food, a bitter taste peculiar to valine is easy toreduce.

In order that glutamic acid may be flavored in the hydrated food of theinvention, pyroglutamic acid and leucine have a mass ratio (that is,pyroglutamic acid/leucine) ranging from about 0.03% to about 80%,preferably ranges from about 0.2% to about 40%, more preferably rangesfrom about 2% to about 20%. When such an amount of pyroglutamic acid isadded to the hydrated food, a bitter taste peculiar to glutamine is easyto reduce.

In order that isoleucine may be flavored in the hydrated food of theinvention, pyroglutamic acid and isoleucine have a mass ratio (that is,pyroglutamic acid/isoleucine) ranging from about 0.1% to about 300%,preferably ranges from about 1% to about 200%, more preferably rangesfrom about 10% to about 100%. When such an amount of pyroglutamic acidis added to the hydrated food, a bitter taste peculiar to valine is easyto reduce.

In order that acesulfame K may be flavored in the hydrated food of theinvention, pyroglutamic acid and acesulfame K have a mass ratio (thatis, pyroglutamic acid/acesulfame K) ranging from about 100% to about10000%, preferably ranges from about 50% to about 5000%, more preferablyranges from about 10% to about 1000%. When such an amount ofpyroglutamic acid is added to the hydrated food, a bitter taste peculiarto acesulfame K is easy to reduce.

In order that aspartame may be flavored in the hydrated food of theinvention, pyroglutamic acid and aspartame have a mass ratio (that is,pyroglutamic acid/aspartame) ranging from about 100% to about 10000%,preferably ranges from about 50% to about 5000%, more preferably rangesfrom about 10% to about 1000%. When such an amount of pyroglutamic acidis added to the hydrated food, a bitter taste peculiar to aspartame iseasy to reduce.

In order that L-phenylalanine may be flavored in the hydrated food ofthe invention, pyroglutamic acid and L-phenylalanine have a mass ratio(that is, pyroglutamic acid/L-phenylalanine) ranging from about 10% toabout 1000%, preferably ranges from about 5% to about 500%, morepreferably ranges from about 1% to about 100%. When such an amount ofpyroglutamic acid is added to the hydrated food, a bitter taste peculiarto L-phenylalanine is easy to reduce.

In order that peptide may be flavored in the hydrated food of theinvention, pyroglutamic acid and peptide have a mass ratio (that is,pyroglutamic acid/peptide) ranging from about 1% to about 800%,preferably ranges from about 5% to about 400%, more preferably rangesfrom about 10% to about 200%. When such an amount of pyroglutamic acidis added to the hydrated food, a bitter taste peculiar toL-phenylalanine is easy to reduce.

The hydrated food of the invention may contain simple sugar used inordinary foods or the like, nonreducing sugar, natural sweetener,artificial sweetener, polysaccharide, food fiber and gelling agent. Forexample, one is selected and used from the following: pentose such asglucose, fructose, galactose, mannose, ribose, deoxyribose and the like;hexose such as glucose, fructose, galactose and the like; arabinose,sucrose, purified sucrose, lactose, sweet tea, fructose, low-fructosecorn syrup, high-fructose syrup, high-fructose corn syrup, starch syrup,muscovado, honey, refined honey, isomerized sugar syrup, simple syrup,trehalose, erythritol, sorbitol, maltitol, palatinose, xylitol,sucralose, saccharin, saccharin sodium, glycyrrhizic acid, monoammoniumglycyrrhizinate, diammonium glycyrrhizinate, dipotassiumglycyrrhizinate, disodium glycyrrhizinate, triammonium glycyrrhizinate,oligosaccharide, carrageenan, agar, gelatin, pectine, xanthan gum, alginacid, alginate solutions, CMC, or the like.

The hydrated food of the invention may generally contain flavoringsubstances used in a food or the like. As such flavoring substances areexemplified various types of flavors, for example, lemon flavor, orangeflavor, grapefruit flavor, chocolate flavor, dl-menthol, l-menthol orthe like.

Furthermore, the hydrated food of the invention may be used with naturalmedicines, herbs, amino acids, peptide, vitamins, minerals, other foods,materials allowed as pharmaceutical products. There is no specificlimitation to such natural medicines. However, for example, the naturalmedicines may include valenian, angelicae radix, paeoniae radix, treepeony, ginseng, etc.

There is no specific limitation to the amino acid to be used. However,for example, the amino acid may include glycine, alanine, praline,hydroxyproline, histidine, arginine, lysine, hydroxylysine, tyrosine,triptophan, asparagines, asparagine acid, glutamine, glutamic acid,hydroxyproline, serine, threonine, methionine, cysteine, natural orsynthetic cystine

There is no specific limitation to the herb. However, for example, theherb may include anise, carrot seed, cloves, coriander, cypress,cinnamon, juniper, ginger, sweet orange, basil, patchouli, bitterorange, fennel, black pepper, bay, peppermint, bergamot, mandarin,myrrh, lemon grass, rosemary, vanilla, hyssop, eucalyptus, lime, lemon,ylangylang, cardamom, clarysage, jasmine, geranium, Bulgarian rose,rose, olibanum, matricaria, sandalwood, verbena, petit grain, vetiverazizanoides, marjoram, Melissa officinelis, rosewood, Hypericum, St.Jones Wart and kava kava.

There is no specific limitation to the vitamin. However, for example,the vitamin may include vitamin A, vitamin B1, vitamin B2, vitamin B6,vitamin B12, vitamin C, vitamin D, vitamin E, vitamin K, folic acid,niacin, lipoic acid, pantothenic acid, biotin and ubiquinone. VitaminB1, B6 and B12 are more preferable. Furthermore, the vitamins includethe derivatives thereof.

There is no specific limitation to the mineral. However, for example,the mineral may include calcium, iron, magnesium, copper, zinc, seleniumand potassium.

Furthermore, the following material may be used with the tablet of theinvention: aloe, royal jelly, placenta, propolis, isoflavone, soyisoflavone, egg yolk lecithin, lecithin, chondroithin, cacao mass,collagen, vinegar, chlorella, spirulina, ginkgo leaf, green tea, hardyrubber tree, oolong tea, mulberry leaf, Rubus suavissimus, Lagerstroemiaspeciosa, unsaturated fatty acid, saccharide such as sugar alcohol andoligosaccharide, fungi such as bifidus bacillus, mushrooms such asagaricus, agaricus blazei Murrill, blacket fungus of the genus Fores,Grifola frondose, fruit such as blueberry, prune, grape, olive and plum,molokheiya such as peanut, almonde, sesame and pepper, vegetables suchas green pepper, cayenne pepper, welsh onion, pumpkin, gourd, carrot,burdock, molokheiya, garlic, beefsteak plant, Japanese horseradish,tomato, scallion, leaf vegetables, sweet potato and beans, seaweeds suchas “wakame” seaweed, fish and shellfish, meat of beast, birds and whalesand grains. Furthermore, usable are extracts, dried products, coarseproduct, refined product, processed product and distilled product.

The hydrated food of the invention may include oral foods such asbeverages, jelly or the like manufactured by dispensing artificialcolorant, preservative, antioxidant, thickening/stabilization agent,emulsifier, gelling agent or the like usually used in food manufacture,if necessary.

The hydrated food of the invention may include necessary foodstuff suchas lipid, electrolyte or the like other than aforesaid acidifiers,sweeteners, amino acids, fragrant materials, herbs, vitamins andmineral.

EFFECT OF THE INVENTION

According to the present invention, the dehydrated food can be providedwhich is superior in a long period preservation and stability oftheanine and can improve a taste threshold of food and flavor the foodwith respect to peculiar taste.

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiments of the present invention will be described in detail.However, the technical scope of the invention should not be limited bythe following description of embodiments but can be practiced in variousmodified forms. Furthermore, it is noted that the technical scope of theinvention should encompass the scope of equivalence.

Embodiment 1 Manufacture of Theanine by Enzyme Method

0.3 M glutamine and 1.5 M methylamine hydrochloride were reacted in thepresence of 0.3 U glutaminase (commercially available) at 30° C. for 22hours in a buffer solution of 0.05 M boric acid (pH 11), whereby 225 nmtheanine was obtained. Reaction liquid was applied to Dowex 50×8columnar chromatography and Dowex 1×2 columnar chromatography (both madeby Muromachi Chemical Co., Ltd.) thereby to be processed by ethanol,whereby an object substance is isolated from the reaction liquid.

The isolated substance was applied to an amino acid analyzer (made byHitachi Co.) and paper chromatography. Since the isolated substancebehaved in the same way as a standard substance, it was recognized asL-theanine. When the isolated substance was processed by hydrolysisusing hydrochloric acid or glutaminase, glutamine acid and ethylaminewere produced in a ratio of 1:1. Thus, since the isolated substance washydrolyzed by glutaminase, it was shown that ethylamine was γ-ethylamineof glutamine acid. Furthermore, it was confirmed on the basis ofglutamate dehydrogenase that glutamine acid produced by hydrolysis wasL-glutamine acid. As a result, 8.5 g theanine was obtained.

Embodiment 2 Extraction of Theanine from Tea Leaves

10 kg tea leaf (Camellia sinensis) was extracted using heated water andthereafter, the obtained extract was passed through a cation exchangeresin (type HCR W-2 made by Muromachi Chemical Industry Co., Ltd.) so asto be eluted by 1N NaOH. Eluted fraction was passed through activatedcharcoal (Taiko activated charcoal SG made by Futamura Chemical IndustryCo., Ltd. The fraction eluted by 15% ethanol was concentrated using anRO film (type NTR 729 HF made by Nitto Denko Corporation). Theconcentrated eluted fraction was refined by columnar chromatography andthen re-crystallized such that 24.8 g theanine was obtained.

L-theanine (product name: Suntheane made by Taiyo Kagaku Co., Ltd.) andvaline (manufactured by Ajinomoto Co. Inc.) were used in the followingexperiments and production of each composition.

Embodiment 3 Theanine Solution Preparation 1

10 mM citric acid solution and acetic acid were suitable mixed togetherand prepared so that pH of the mixture became 2.0. 200 mg L-theanine wasadded to 100 mL of the prepared solution to be dissolved and thereafterpassed through a 0.45 um filter, whereby 2 mg/mL L-theanine solutionwith pH of 2.0 was prepared.

Embodiment 4 Theanine Solution Preparation 2

10 mM citric sodium solution and 10 mM citric acid solution weresuitably mixed together to be prepared so that pH of the mixture became2.8, whereby a citric buffer fluid was prepared. 200 mg of L-theaninewas added to 100 mL of the buffer fluid to be dissolved and thereafterpassed through a 0.45 μm filter, whereby 2 mg/mL L-theanine solutionwith pH of 2.8 was prepared.

Embodiment 5 Theanine Solution Preparation 3

10 mM citric sodium solution and 10 mM citric acid solution weresuitably mixed together to be prepared so that pH of the mixture became4.3, whereby a citric buffer fluid was prepared. 200 mg of L-theaninewas added to 100 mL of the buffer fluid to be dissolved and thereafterpassed through a 0.45 μm filter, whereby 2 mg/mL L-theanine solutionwith pH of 4.3 was prepared.

Embodiment 6 Theanine Solution Preparation 4

10 mM citric sodium solution and 10 mM citric acid solution weresuitably mixed together to be prepared so that pH of the mixture became5.5, whereby a citric buffer fluid was prepared. 200 mg of L-theaninewas added to 100 mL of the buffer fluid to be dissolved and thereafterpassed through a 0.45 μm filter, whereby 2 mg/mL L-theanine solutionwith pH of 5.5 was prepared.

Embodiment 7 Theanine Solution Preparation 5

3 N hydrochloric acid was added to 10 mM sodium dihydrogen phosphatesolution and prepared so that pH of the solution became 7.5. 200 mgL-theanine was added to 100 mL of the prepared solution to be dissolvedand thereafter passed through a 0.45 μm filter, whereby 2 mg/mLL-theanine solution with pH of 7.5 was prepared.

Embodiment 8 Theanine Solution Preparation 6

10 mM citric sodium solution and 10 mM citric acid solution weresuitably mixed together to be prepared so that pH of the mixture became4.3, whereby a citric buffer fluid was prepared. 10 mg, 50 mg, 100 mg,200 mg, 400 mg and 600 mg of L-theanine was each added to 100 mL of thebuffer fluid to be dissolved and thereafter passed through a 0.45 μmfilter, whereby 0.1 mg/mL, 0.5 mg/mL, 1 mg/mL, 2 mg/mL and 4 mg/mL and 6mg/mL L-theanine solution with pH of 4.3 was prepared.

Embodiment 9 Pyroglutamic-Acid Containing Theanine Solution Preparation1

0%, 0.5%, 1%, 25%, 50%, 100%, 150% and 200% pyroglutamic acid was addedto the theanine solution of embodiment 4 with pH of 2.8 relative totheanine and dissolved and agitated, and thereafter passed through a0.45 μm filter, whereby pyroglutamic-acid containing theanine solutionwith pH of 2.8 was prepared. The pyroglutamic acid was made by AJINOMOTOCO., INC.

Embodiment 10 Pyroglutamic-Acid Containing Theanine Solution Preparation2

0%, 0.5%, 1%, 25%, 50%, 100%, 150% and 200% pyroglutamic acid was addedto the theanine solution of embodiment 4 with pH of 7.5 relative totheanine and dissolved and agitated, and thereafter passed through a0.45 μm filter, whereby pyroglutamic-acid containing theanine solutionwith pH of 7.5 was prepared.

Embodiment 11 Determination of Quantity of Theanine by HPLC

Theanine content in theanine solution prepared in each embodiment wasdetermined using a high performance liquid chromatography (HPLC).Conditions of quantitative determination of HPLC are shown by thefollowing table.

TABLE 1 Column Develosil ODS HG-5/Nomura Kagaku Co., LTD. DetectorWaters 2487 dual λ UV/VIS detector/Waters Co., LTD. Theanine standardL-theanine/Kurita Kogyo Co., LTD. internal standardNicotineamide/Nakaraitesuku Co., LTD. mobile phase water:methanol:TFA =980:20:1

Embodiment 12 Preparation of Beverage

A pyroglutamic-acid added beverage was prepared using components asshown in the following TABLE 2. More specifically, to 8 L purified waterwere agitated and dissolved L-theanine, guagum degradation product(trade name: “Sunfiber HG” made by TAIYO KAGAKU CO., LTD.), pyroglutamicacid, DL-malic acid, granulated sugar, low-fructose corn syrup and ⅕concentrated apple juice while being sequentially added to. Fragrance,citric sodium and purified water were added to the solution so that pHbecame 4.5. A total quantity of solution was set to 10 L and thereafterpassed through a 0.22 μm sterilization filter. The solution was put intobistered bottles each having a content of 100 mL. A beverage containing400 mg L-theanine per bottle was produced. Furthermore, a beveragecontaining no pyroglutamic acid was also produced.

TABLE 2 pyroglutamic acid pyroglutamic acid (—) 0.1% Component (percentby mass) (percent by mass) L-theanine 0.4 0.4 pyroglutamic acid — 0.1guagum degradation 1.0 1.0 product DL-malic acid 0.05 0.05 granulatedsugar 2.0 2.0 low-fructose corn 3.0 3.0 syrup ⅕ concentrated 0.2 0.2apple juice fragrance 0.1 0.1 citric sodium pH adjuster pH adjusterpurified water a proper amount a proper amount

Embodiment 13 Preparation of Jelly Beverage

A jelly beverage added with pyroglutamic-acid was prepared usingcomposition as shown in the following TABLE 3. More specifically, withpurified water were mixed a gelling agent (trade name: “Neosoft DAR”made by TAIYO KAGAKU CO., LTD.), L-theanine, pyroglutamic acid,granulated sugar and maltose water candy. The mixture was heated at 85°C. and dissolved and thereafter, mango puree, ⅕ concentrated lemonjuice, fragrance and citric sodium were added to the mixture andprepared to pH of 4.5. The prepared mixture was processed by one-minuteplate sterilization at 94° C., filtrated by the use of a 100-mesh filterand thereafter put into flexible pouches, whereby the jelly beverage wasprepared. Furthermore, another jelly beverage added with no pyroglutamicacid was made as a comparative example.

TABLE 3 pyroglutamic acid pyroglutamic acid (—) 0.1% Component (percentby mass) (percent by mass) gelling agent 0.5 0.5 L-theanine 0.2 0.2pyroglutamic acid — 0.1 granulated sugar 3.0 3.0 maltose water candy25.0 25.0 mango puree 20.0 20.0 ⅕ concentrated 0.3 0.3 lemon juicefragrance 0.1 0.1 citric sodium pH adjuster pH adjuster purified water aproper amount a proper amount

Test Example 1 Preservation Test

Theanine solution of each of embodiments 3 to 10 was put into atransparent and colorless vial every 20 mL and preserved in an incubatorat 55° C. for six weeks.

Furthermore, the beverage of embodiment 12 and jelly beverage ofembodiment 13 were also preserved in the incubator at 55° C. for sixweeks.

Test Example 2 Comparison of Stability in Content of Theanine withDifferent pH's

Samples of the theanine solutions of embodiments 3 to 7 were preservedin the manner of preservation test of test example 1 and evaluated bythe theanine measurement method described in embodiment 11. FIG. 1 showstheanine content in the solution of each embodiment after end of thepreservation test.

As shown in the figure, after end of the preservation test, theconcentration of theanine solution of embodiment 3 was reduced to about40% of an initially loaded quantity (2 mg/mL) and accordingly lacked forstability. The concentration of theanine solution of embodiment 4 afterthe end of preservation test was reduced to about 74% of the initiallyloaded quantity. The concentration of theanine solution of embodiment 5was reduced to about 80%. The concentration of theanine solution ofembodiment 6 was reduced to about 90%. When compared with the results ofthe solution of embodiment 3, each embodiment was improved in thestability of theanine. The solution of embodiment 7 was reduced to about76% of the initially loaded quantity and was more stable as comparedwith the solution of embodiment 3.

Test Example 3 Comparison of Stability with Changes in TheanineConcentration (pH 4.3)

Samples of the theanine solution of embodiment 8 were preserved in themanner of preservation test of test example 1 and evaluated by thetheanine measurement method described in embodiment 11. FIG. 2 showstheanine content after end of the preservation test.

The axis of abscissas in the figure designates theanine concentration.No changes in the stability with changes in the theanine concentrationwere recognized as shown in the figure.

Test Example 4 Comparison of Stability of Theanine with Addition ofPyroglutamic Acid (pH 2.8)

Samples of the theanine solution of embodiment 9 were preserved in themanner of preservation test of test example 1 and evaluated by thetheanine measurement method described in embodiment 11. FIG. 3 showstheanine content after end of the preservation test.

The axis of abscissas in the figure designates concentration ofpyroglutamic acid relative to theanine content. When no pyroglutamicacid was contained (no addition), a residual ratio of theanine was about75%. When pyroglutamic acid was added by 0.5% relative to theaninecontent, the stability of theanine was slightly improved (77%).Furthermore, the residual ratio of theanine was improved with increasein an amount of added pyroglutamic acid relative to theanine content.When the ratio of pyroglutamic acid/theanine was not less than 50%, theresidual ratio of theanine was not less than 86%, whereupon remarkablestabilizing action was recognized.

Test Example 5 Comparison of Stability of Theanine with Addition ofPyroglutamic Acid (pH 7.5)

Samples of the theanine solution of embodiment 10 were preserved in themanner of preservation test of test example 1 and evaluated by thetheanine measurement method described in embodiment 11. FIG. 4 showstheanine content after end of the preservation test.

The axis of abscissas in the figure designates concentration ofpyroglutamic acid relative to theanine content. When no pyroglutamicacid was contained (no addition), a residual ratio of theanine was about92%.

On the other hand, when pyroglutamic acid was added by 1.0% relative totheanine content, the stability of theanine was about 94%.

Thus, as in test example 6, stabilization of theanine due to addition ofpyroglutamic acid was recognized although the addition was small.

Test Example 6 Comparison of Stability of Theanine in Beverage withAddition of Pyroglutamic Acid

Samples of the beverage of embodiment 12 were preserved in the manner ofpreservation test of test example 1 and evaluated by the theaninemeasurement method described in embodiment 11. TABLE 4 shows theaninecontent after end of the preservation test. In the compared example, 321mg/100 mL (about 80%) of theanine remained when an initial amount ofadded theanine was 400 mg/100 mL. On the other hand, 356 mg/100 mL(about 90%) of theanine remained in embodiment 12 of addition ofpyroglutamic acid.

TABLE 4 no pyroglutamic acid pyroglutamic acid 0.1% theanine content 321mg/100 mL 356 mg/100 mL

Test Example 7 Comparison of Stability of Theanine in Jelly Beveragewith Addition of Pyroglutamic Acid

Samples of the jelly beverage of embodiment 13 were preserved in themanner of preservation test of test example 1 and evaluated by thetheanine measurement method described in embodiment 11. TABLE 5 showstheanine content after end of the preservation test. In the comparedexample, 164 mg/100 mL (about 82%) of theanine remained afterpreservation when an initial amount of added theanine was 200 mg/100 mL.On the other hand, 183 mg/100 mL (about 92%) of theanine remained inembodiment 13 of addition of pyroglutamic acid.

TABLE 5 no pyroglutamic acid pyroglutamic acid 0.1% theanine content 164mg/100 mL 183 mg/100 mL

Test Example 8 Changes in Theanine Threshold with Addition ofPyroglutamic Acid

A sensory evaluation was carried out for changes in the taste thresholdof theanine due to pyroglutamic acid. Ten panelists were invited toinvestigate whether the panelists felt the taste of theanine whenpyroglutamic acid was added to a theanine solution. TABLE 6 shows thenumber of panelists who felt the taste of theanine at respectiveconcentrations of theanine and pyroglutamic acid.

TABLE 6 pyroglutamic acid theanine (mg/100 ml) (mg/100 ml) 0 1 10 50 1000 0 0 0 0 0 100 0 0 0 0 0 150 8 2 0 0 0 500 10 3 1 0 0 1000 10 5 3 1 0

Eight of the ten panelists felt the taste of theanine when theconcentration of theanine was 150 mg/100 ml, which value was a thresholdof theanine. When 1 mg/100 ml pyroglutamic acid was added to thetheanine solution, six of the above eight panelists did not feel thetaste of theanine. None of the panelists felt the taste of theanine when10 mg/100 ml pyroglutamic acid was added to the theanine solution. Evenwhen 100 mg/100 ml pyroglutamic acid was added to the theanine solutionwith the concentration of 1000 mg/100 ml, the taste of theanine was notfelt. Additionally, none of the panelists felt the taste of pyroglutamicacid when 100 mg/100 ml pyroglutamic acid was dissolved into thesolution.

Test Example 9 Changes in Glutamine Threshold with Addition ofPyroglutamic Acid

A sensory evaluation was carried out for changes in the taste thresholdof glutamine due to pyroglutamic acid. Ten panelists were invited toinvestigate whether the panelists felt the taste of glutamine whenpyroglutamic acid was added to a glutamine solution. The glutamine wasmade by AJINOMOTO CO., INC. TABLE 7 shows the number of panelists whofelt the taste of glutamine at respective concentrations of glutamineand pyroglutamic acid.

TABLE 7 pyroglutamic acid glutamine (mg/100 ml) (mg/100 ml) 0 1 10 50100 0 0 0 0 0 0 150 0 0 0 0 0 250 7 3 0 0 0 500 10 4 2 0 0 1000 10 5 2 10

Seven of the ten panelists felt the taste of glutamine when theconcentration of glutamine was 250 mg/100 ml, which value was athreshold of glutamine. When 1 mg/100 ml pyroglutamic acid was added tothe glutamine solution, four of the above seven panelists did not feelthe taste of glutamine. None of the panelists felt the taste ofglutamine when 10 mg/100 ml pyroglutamic acid was added to the glutaminesolution. Even when 100 mg/100 ml pyroglutamic acid was added to theglutamine solution with the concentration of 1000 mg/100 ml, the tasteof glutamine was not felt. Additionally, none of the panelists felt thetaste of pyroglutamic acid when 100 mg/100 ml pyroglutamic acid wasdissolved into the solution.

Test Example 10 Changes in Glutamic Acid Threshold with Addition ofPyroglutamic Acid

A sensory evaluation was carried out for changes in the taste thresholdof glutamic acid due to pyroglutamic acid. Ten panelists were invited toinvestigate whether the panelists felt the taste of glutamic acid whenpyroglutamic acid was added to a glutamine solution. The glutamic acidwas made by AJINOMOTO CO., INC. TABLE 8 shows the number of panelistswho felt the taste of glutamic acid at respective concentrations ofglutamic acid and pyroglutamic acid.

TABLE 8 glutamic pyroglutamic acid acid (mg/100 ml) (mg/100 ml) 0 1 1050 100 0 0 0 0 0 0 1 0 0 0 0 0 5 9 4 2 0 0 10 10 5 2 0 0 20 10 7 5 3 0

Nine of the ten panelists felt the taste of glutamine when theconcentration of glutamic acid was 5 mg/100 ml, which value was athreshold of glutamic acid. When 1 mg/100 ml pyroglutamic acid was addedto the glutamic acid solution, five of the above nine panelists did notfeel the taste of glutamic acid. None of the panelists felt the taste ofglutamic acid when 50 mg/100 ml pyroglutamic acid was added to theglutamine solution. Even when 100 mg/100 ml pyroglutamic acid was addedto the glutamic acid solution with the concentration of 100 mg/100 ml,the taste of glutamine was not felt. Additionally, none of the panelistsfelt the taste of pyroglutamic acid when 100 mg/100 ml pyroglutamic acidwas dissolved into the solution.

Test Example 11 Changes in Valine Threshold with Addition ofPyroglutamic Acid and Theanine

A sensory evaluation was carried out for changes in the taste thresholdof glutamine due to pyroglutamic acid. Ten panelists were invited toinvestigate whether the panelists felt the taste of glutamine whenpyroglutamic acid was added to a glutamine solution. The glutamine wasmade by AJINOMOTO CO., INC. TABLE 7 shows the number of panelists whofelt the taste of glutamine at respective concentrations of glutamineand pyroglutamic acid.

TABLE 9 pyroglutamic acid/ valine theanine (mg/100 ml) (mg/100 ml) 0 110 50 100 0 0 0 0 0 0 100 0 0 0 0 0 150 8 2 0 0 0 500 10 3 1 0 0 1000 105 3 1 0

Eight of the ten panelists felt the bitter taste of valine when theconcentration of valine was 150 mg/100 ml, which value was a thresholdof valine. When 1 mg/100 ml mixture of glutamic acid and theanine wasadded to the valine solution, six of the above eight panelists did notfeel the bitter taste of valine. None of the panelists felt the bittertaste of valine when 10 mg/100 ml mixture was added to the valinesolution. Even when 100 mg/100 ml mixture was added to the Valinesolution with the concentration of 1000 mg/100 ml, the bitter taste ofvaline was not felt. Additionally, none of the panelists felt the tasteof mixture of pyroglutamic acid and theanine when 100 mg/100 mlpyroglutamic acid was dissolved into the solution.

Test Example 12 Changes in Leucine Threshold with Addition ofPyroglutamic Acid and Theanine

A sensory evaluation was carried out for changes in the taste thresholdof leucine due to pyroglutamic acid and theanine. Ten panelists wereinvited to investigate whether the panelists felt the bitter taste ofleucine when pyroglutamic acid and theanine were added to a leucinesolution. The leucine was made by AJINOMOTO CO., INC. TABLE 10 shows thenumber of panelists who felt the taste of leucine at respectiveconcentrations of mixtures (mixing weight ratio: pyroglutamicacid:theanine=1:50) of leucine, pyroglutamic acid and theanine.

TABLE 10 pyroglutamic acid/ leucine theanine (mg/100 ml) (mg/100 ml) 0 110 50 100 0 0 0 0 0 0 200 0 0 0 0 0 380 5 1 0 0 0 500 7 2 0 0 0 1000 103 1 0 0

Five of the ten panelists felt the bitter taste of leucine when theconcentration of leucine was 380 mg/100 ml, which value was a thresholdof leucine. When 1 mg/100 ml mixture of pyroglutamic acid and theaninewas added to the leucine solution, four of the above five panelists didnot feel the bitter taste of leucine. None of the panelists felt thebitter taste of leucine when 10 mg/100 ml mixture was added to theleucine solution. Even when 100 mg/100 ml mixture was added to theleucine solution with the concentration of 1000 mg/100 ml, the bittertaste of leucine was not felt. Additionally, none of the panelists feltthe taste of mixture of pyroglutamic acid and theanine when 100 mg/100ml mixture of pyroglutamic acid and theanine was dissolved into thesolution.

Test Example 13 Changes in Isoleucine Threshold with Addition ofPyroglutamic Acid and Theanine

A sensory evaluation was carried out for changes in the taste thresholdof isoleucine due to pyroglutamic acid and theanine. Ten panelists wereinvited to investigate whether the panelists felt the bitter taste ofisoleucine when pyroglutamic acid and theanine were added to anisoleucine solution. The isoleucine was made by AJINOMOTO CO., INC.TABLE 11 shows the number of panelists who felt the bitter taste ofisoleucine at respective concentrations of mixtures (mixing weightratio: pyroglutamic acid:theanine=1:50) of isoleucine, pyroglutamic acidand theanine.

TABLE 11 pyroglutamic acid/ isoleucine theanine (mg/100 ml) (mg/100 ml)0 1 10 50 100 0 0 0 0 0 0 50 0 0 0 0 0 90 7 4 1 0 0 200 9 4 1 0 0 500 106 4 3 0

Seven of the ten panelists felt the bitter taste of isoleucine when theconcentration of isoleucine was 90 mg/100 ml, which value was athreshold of leucine. When 1 mg/100 ml mixture of pyroglutamic acid andtheanine was added to the isoleucine solution, three of the above sevenpanelists did not feel the bitter taste of isoleucine. None of thepanelists felt the bitter taste of isoleucine when 50 mg/100 ml mixturewas added to the isoleucine solution. Even when 100 mg/100 ml mixturewas added to the isoleucine solution with the concentration of 500mg/100 ml, the bitter taste of isoleucine was not felt. Additionally,none of the panelists felt the taste of mixture of pyroglutamic acid andtheanine when 100 mg/100 ml pyroglutamic acid was dissolved into thesolution.

Test Example 14 Changes in Acesulfame K Threshold with Addition ofPyroglutamic Acid and Theanine

A sensory evaluation was carried out for changes in the taste thresholdof acesulfame K due to pyroglutamic acid and theanine. Ten panelistswere invited to investigate whether the panelists felt the taste ofacesulfame K when pyroglutamic acid and theanine were added to anacesulfame K solution. The acesulfame K was made by TAKEDA-KIRIN FOODSCORPORATION. TABLE 12 shows the number of panelists who felt the bittertaste of acesulfame K at respective concentrations of mixtures (mixingweight ratio: pyroglutamic acid:theanine=1:50) of isoleucine,pyroglutamic acid and theanine.

TABLE 12 pyroglutamic acid/ acesulfame K theanine (mg/100 ml) (mg/100ml) 0 1 10 50 100 0 0 0 0 0 0 1 0 0 0 0 0 3 7 3 0 0 0 5 9 4 1 0 0 10 106 2 1 0

Seven of the ten panelists felt the bitter taste of acesulfame K whenthe concentration of acesulfame K was 3 mg/100 ml, which value was athreshold of acesulfame K. When 1 mg/100 ml mixture of pyroglutamic acidand theanine was added to the acesulfame K solution, four of the aboveseven panelists did not feel the bitter taste of acesulfame K. None ofthe panelists felt the bitter taste of acesulfame K when 10 mg/100 mlmixture was added to the acesulfame K solution. Even when 100 mg/100 mlmixture was added to the acesulfame K solution with the concentration of10 mg/100 ml, the bitter taste of acesulfame K was not felt.Additionally, none of the panelists felt the taste of mixture ofpyroglutamic acid and theanine when 100 mg/100 ml mixture ofpyroglutamic acid and theanine was dissolved into the solution.

Test Example 15 Changes in Aspartame Threshold with Addition ofPyroglutamic Acid and Theanine

A sensory evaluation was carried out for changes in the taste thresholdof aspartame due to pyroglutamic acid and theanine. Ten panelists wereinvited to investigate whether the panelists felt the taste of aspartamewhen pyroglutamic acid and theanine were added to an aspartame solution.The aspartame was made by AJINOMOTO CO., INC. TABLE 13 shows the numberof panelists who felt the bitter taste of aspartame at respectiveconcentrations of mixtures (mixing weight ratio: pyroglutamicacid:theanine=1:50) of aspartame, pyroglutamic acid and theanine.

TABLE 13 pyroglutamic acid/ aspartame theanine (mg/100 ml) (mg/100 ml) 01 10 50 100 0 0 0 0 0 0 1 0 0 0 0 0 3 7 4 0 0 0 5 10 2 1 0 0 10 10 4 3 10

Seven of the ten panelists felt the bitter taste of aspartame when theconcentration of aspartame was 3 mg/100 ml, which value was a thresholdof aspartame. When 1 mg/100 ml mixture of pyroglutamic acid and theaninewas added to the aspartame solution, three of the above seven panelistsdid not feel the bitter taste of aspartame. None of the panelists feltthe bitter taste of aspartame when 10 mg/100 ml mixture was added to theaspartame solution. Even when 100 mg/100 ml mixture was added to theaspartame solution with the concentration of 10 mg/100 ml, the bittertaste of aspartame was not felt. Additionally, none of the panelistsfelt the taste of mixture of pyroglutamic acid and theanine when 100mg/100 ml mixture of pyroglutamic acid and theanine was dissolved intothe solution.

Test Example 16 Changes in L-phenylalanine Threshold with Addition ofPyroglutamic Acid and Theanine

A sensory evaluation was carried out for changes in the taste thresholdof L-phenylalanine due to pyroglutamic acid and theanine. Ten panelistswere invited to investigate whether the panelists felt the taste ofL-phenylalanine when pyroglutamic acid and theanine were added to anL-phenylalanine solution. The L-phenylalanine was made by AJINOMOTO CO.,INC. TABLE 14 shows the number of panelists who felt the bitter taste ofL-phenylalanine at respective concentrations of mixtures (mixing weightratio: pyroglutamic acid:theanine=1:50) of aspartame, pyroglutamic acidand theanine.

TABLE 14 pyroglutamic acid/ L-phenylalanine theanine (mg/100 ml) (mg/100ml) 0 1 10 50 100 0 0 0 0 0 0 10 0 0 0 0 0 30 8 1 0 0 0 50 10 3 1 0 0100 10 5 3 1 0

Eight of the ten panelists felt the bitter taste of L-phenylalanine whenthe concentration of L-phenylalanine was 30 mg/100 ml, which value was athreshold of L-phenylalanine. When 1 mg/100 ml mixture of pyroglutamicacid and theanine was added to the L-phenylalanine solution, seven ofthe above eight panelists did not feel the bitter taste ofL-phenylalanine. None of the panelists felt the bitter taste ofL-phenylalanine when 10 mg/100 ml mixture was added to theL-phenylalanine solution. Even when 100 mg/100 ml mixture was added tothe L-phenylalanine solution with the concentration of 100 mg/100 ml,the bitter taste of L-phenylalanine was not felt. Additionally, none ofthe panelists felt the taste of mixture of pyroglutamic acid andtheanine when 100 mg/100 ml mixture of pyroglutamic acid and theaninewas dissolved into the solution.

Test Example 17 Changes in Albumen Peptide Threshold with Addition ofPyroglutamic Acid and Theanine

A sensory evaluation was carried out for changes in the bitter tastethreshold of albumen peptide due to pyroglutamic acid and theanine. Tenpanelists were invited to investigate whether the panelists felt thebitter taste of albumen peptide when pyroglutamic acid and theanine wereadded to an albumen peptide solution. Trade name, “RunPep” made byPharma Foods International Co., Ltd. was used as the albumen peptide.TABLE 15 shows the number of panelists who felt the bitter taste ofalbumen peptide at respective concentrations of mixtures (mixing weightratio: pyroglutamic acid:theanine=1:50) of albumen peptide, pyroglutamicacid and theanine.

TABLE 15 pyroglutamic acid/ albumen peptide theanine (mg/100 ml) (mg/100ml) 0 1 10 50 100 0 0 0 0 0 0 100 0 0 0 0 0 1000 9 4 0 0 0 3000 10 5 0 00 5000 10 7 4 2 0

Nine of the ten panelists felt the bitter taste of albumen peptide whenthe concentration of albumen peptide was 1000 mg/100 ml, which value wasa threshold of albumen peptide. When 1 mg/100 ml mixture of pyroglutamicacid and theanine was added to the albumen peptide solution, five of theabove nine panelists did not feel the bitter taste of albumen peptide.None of the panelists felt the bitter taste of albumen peptide when 10mg/100 ml mixture was added to the albumen peptide solution. Even when100 mg/100 ml mixture was added to the albumen peptide solution with theconcentration of 500 mg/100 ml, the bitter taste of albumen peptide wasnot felt. Additionally, none of the panelists felt the taste of mixtureof pyroglutamic acid and theanine when 100 mg/100 ml mixture ofpyroglutamic acid and theanine was dissolved into the solution.

Thus, according to the present invention, the hydrated food can beprovided in which theanine content can stably be maintained even whenthe hydrated food is preserved for a long period of time. Furthermore,the hydrated food can be provided in which the taste threshold of thefood can be improved and the peculiar taste can be flavored.

<Specific Forms>

Specific forms of the present invention are as follows:

(1) A hydrated food characterized in that theanine is L-theanine;

(2) A hydrated food characterized in that the theanine content rangesfrom about 0.03 mg/mL to about 200 mg/mL, and the pyroglutamine contentranges from about 1% to about 200% relative to the theanine content;

(3) A hydrated food characterized in that the theanine content rangesfrom about 1.5 mg/mL to about 200 mg/mL, and the pyroglutamine contentranges from about 1% to about 200% relative to the theanine content;

(4) A hydrated food characterized in that in the above (2), pH rangesfrom about 2.8 to about 7.5;

(5) A hydrated food characterized in that the hydrated food is a juice;and

(6) A hydrated food characterized in that the hydrated food is a jellybeverage.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 A graph showing the residual ratio of theanine after thepreservation test with respect to theanine solutions of embodiments 3 to7;

FIG. 2 A graph showing the residual ratio of theanine after thepreservation test with respect to theanine solution of embodiment 8;

FIG. 3 A graph showing the residual ratio of theanine after thepreservation test with respect to pH 2.8 theanine solution to whichpyroglutamic acid ranging from 0% to 200% is added; and

FIG. 4 A graph showing the residual ratio of theanine after thepreservation test with respect to pH 7.5 theanine solution to whichpyroglutamic acid ranging from 0% to 200% is added.

1. A hydrated food characterized by containing (A) pyroglutamic acid. 2.A hydrated food characterized by containing one or more amino acidsselected from groups comprising (A) pyroglutamic acid, (B) theanine,glutamine and glutamic acid.
 3. A hydrated food characterized bycontaining one or more amino acids selected from groups comprising (A)pyroglutamic acid, (B) theanine, glutamine and glutamic acid, and (C)branched chain amino acid.
 4. A hydrated food characterized bycontaining one or more amino acids selected from groups comprising (A)pyroglutamic acid, (B) theanine, glutamine and glutamic acid, and one ormore synthetic sweeteners selected from a group of (D) acesulfame K,aspartame and L-phenylalanine.
 5. A hydrated food characterized bycontaining one or more amino acids selected from groups comprising (A)pyroglutamic acid, (B) theanine, glutamine and glutamic acid, and (E)peptide.
 6. The hydrated food according to claim 1, characterized inthat the hydrated food is a beverage having pH ranging from about 2.8 toabout 7.5.
 7. The hydrated food according to claim 1, characterized inthat the hydrated food is a gel food having pH ranging from about 2.8 toabout 7.5.